“The principle of abuse of process is based on the underlying public interest that there should be finality in litigation, and efficiency and economy in the conduct of litigation. The bringing of a claim or the raising of a defence in later proceedings may, without more, amount to an abuse of process if the court is satisfied (the onus being on the party alleging abuse) that the claim or defence should have been raised in earlier proceedings if it was to be raised at all.”
“What is required is a broad, merits-based judgment, taking account of all the facts and circumstances. The proper approach is to ask whether in all the circumstances a party's conduct is an abuse. Although that will often give the same result as asking whether the conduct is an abuse and then, if it is, asking whether the abuse is excused or justified by special circumstances, it will not invariably do so, and it is always necessary for the question of abuse to be considered by reference to all the circumstances of the individual case.”